diff --git a/index.js b/index.js
index b4a475a..357aa91 100644
--- a/index.js
+++ b/index.js
@@ -4,6 +4,7 @@ var downloader = require('s3-download-stream');
 var debug = require('debug')('s3-blob-store');
 var mime = require('mime-types');
 var uploadStream = require('s3-stream-upload');
+var util = require('util');
 
 /**
  * Create S3 blob store
@@ -17,8 +18,6 @@ function S3BlobStore (opts) {
   opts = opts || {};
   if (!opts.client) throw Error('S3BlobStore client option required (aws-sdk AWS.S3 instance)');
   if (!opts.bucket) throw Error('S3BlobStore bucket option required');
-  this.accessKey = opts.accessKey;
-  this.secretKey = opts.secretKey;
   this.bucket = opts.bucket;
   this.s3 = opts.client;
 }
@@ -26,12 +25,13 @@ function S3BlobStore (opts) {
 /**
  * Create read stream
  * @param {ReadStreamOptions|String} opts options or object key
+ * @param {ReadParams} [s3opts] additional S3 options
  * @returns {ReadableStream}
  *   readable stream of data for the file in your bucket whose key matches
  */
-S3BlobStore.prototype.createReadStream = function (opts) {
+S3BlobStore.prototype.createReadStream = function (opts, s3opts) {
   if (typeof opts === 'string') opts = { key: opts };
-  var config = { client: this.s3, params: this.downloadParams(opts) };
+  var config = { client: this.s3, params: this._s3params(opts, s3opts) };
   if (opts.concurrency) config.concurrency = opts.concurrency;
   if (opts.chunkSize) config.chunkSize = opts.chunkSize;
   var stream = downloader(config);
@@ -41,36 +41,10 @@ S3BlobStore.prototype.createReadStream = function (opts) {
   return stream;
 };
 
-S3BlobStore.prototype.uploadParams = function (opts) {
-  opts = Object.assign({}, opts, {
-    params: Object.assign({}, opts.params)
-  });
-
-  var filename = opts.name || opts.filename;
-  var key = opts.key || filename;
-  var contentType = opts.contentType;
-
-  var params = opts.params;
-  params.Bucket = params.Bucket || this.bucket;
-  params.Key = params.Key || key;
-
-  if (!contentType) {
-    contentType = filename ? mime.lookup(filename) : mime.lookup(opts.key);
-  }
-  if (contentType) params.ContentType = contentType;
-
-  return params;
-};
-
-S3BlobStore.prototype.downloadParams = function (opts) {
-  var params = this.uploadParams(opts);
-  delete params.ContentType;
-  return params;
-};
-
 /**
  * Create write stream
  * @param {Options<WriteParams>|String} opts options or object key
+ * @param {WriteParams} [s3opts] additional S3 options
  * @param {function(Error, { key: String })} done callback
  * @returns {WritableStream} writable stream that you can pipe data to
  */
@@ -80,7 +54,9 @@ S3BlobStore.prototype.createWriteStream = function (opts, s3opts, done) {
     s3opts = {};
   }
   if (typeof opts === 'string') opts = { key: opts };
-  var params = this.uploadParams(opts);
+  var params = this._s3params(opts, s3opts);
+  var contentType = (opts && opts.contentType) || mime.lookup(params.Key);
+  if (contentType) params.ContentType = contentType;
   var out = uploadStream(this.s3, params);
   out.on('error', function (err) {
     debug('got err %j', err);
@@ -95,28 +71,63 @@ S3BlobStore.prototype.createWriteStream = function (opts, s3opts, done) {
 
 /**
  * Remove object from store
- * @param {{ key: String }|String} opts options containing object key or just key
+ * @param {Options<RemoveParams>|String} opts options or object key
+ * @param {RemoveParams} [s3opts] additional S3 options
  * @param {function(Error)} done callback
  */
-S3BlobStore.prototype.remove = function (opts, done) {
-  var key = typeof opts === 'string' ? opts : opts.key;
-  this.s3.deleteObject({ Bucket: this.bucket, Key: key }, done);
+S3BlobStore.prototype.remove = function (opts, s3opts, done) {
+  if (typeof s3opts === 'function') {
+    done = s3opts;
+    s3opts = {};
+  }
+  if (typeof opts === 'string') opts = { key: opts };
+  var params = this._s3params(opts, s3opts);
+  this.s3.deleteObject(params, done);
   return this;
 };
 
 /**
  * Check if object exits
- * @param {{ key: String }|String} opts options containing object key or just key
+ * @param {Options<ExistsParams>|String} opts options or object key
+ * @param {ExistsParams} [s3opts] additional S3 options
  * @param {function(Error, Boolean)} done callback
  */
-S3BlobStore.prototype.exists = function (opts, done) {
+S3BlobStore.prototype.exists = function (opts, s3opts, done) {
+  if (typeof s3opts === 'function') {
+    done = s3opts;
+    s3opts = {};
+  }
   if (typeof opts === 'string') opts = { key: opts };
-  this.s3.headObject({ Bucket: this.bucket, Key: opts.key }, function (err, res) {
+  var params = this._s3params(opts, s3opts);
+  this.s3.headObject(params, function (err, _res) {
     if (err && err.statusCode === 404) return done(null, false);
     done(err, !err);
   });
 };
 
+S3BlobStore.prototype._s3params = function (opts, s3opts) {
+  opts = opts || {};
+  opts.params = s3opts || opts.params || {};
+  var key = opts.key || opts.name || opts.filename;
+  var params = Object.assign({}, opts.params, {
+    Bucket: opts.params.Bucket || this.bucket,
+    Key: opts.params.Key || key
+  });
+  return params;
+};
+
+S3BlobStore.prototype.uploadParams = util.deprecate(function (opts) {
+  opts = opts || {};
+  var params = this._s3params(opts);
+  var contentType = opts.contentType || mime.lookup(params.Key);
+  if (contentType) params.ContentType = contentType;
+  return params;
+}, 'S3BlobStore#uploadParams(opts) is deprecated and will be removed in upcoming v5!');
+
+S3BlobStore.prototype.downloadParams = util.deprecate(function (opts) {
+  return this._s3params(opts);
+}, 'S3BlobStore#downloadParams(opts) is deprecated and will be removed in upcoming v5!');
+
 module.exports = S3BlobStore;
 
 /** @typedef {import('stream').Readable} ReadableStream */
@@ -158,3 +169,17 @@ module.exports = S3BlobStore;
  * @name WriteParams
  * @see https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property
  */
+
+/**
+ * S3 `deleteObject` params
+ * @typedef {import('aws-sdk').S3.DeleteObjectRequest} RemoveParams
+ * @name RemoveParams
+ * @see https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#deleteObject-property
+ */
+
+/**
+ * S3 `headObject` params
+ * @typedef {import('aws-sdk').S3.HeadObjectRequest} ExistsParams
+ * @name ExistsParams
+ * @see https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#headObject-property
+ */
diff --git a/readme.md b/readme.md
index 750a15c..dd906ec 100644
--- a/readme.md
+++ b/readme.md
@@ -61,12 +61,14 @@ store.exists({ key: 'somefile.txt' }, function (err, exists) {
         -   [Parameters](#parameters-3)
     -   [exists](#exists)
         -   [Parameters](#parameters-4)
--   [WriteParams](#writeparams)
--   [Options](#options)
-    -   [Properties](#properties)
+-   [ExistsParams](#existsparams)
 -   [ReadStreamOptions](#readstreamoptions)
 -   [S3](#s3)
 -   [ReadParams](#readparams)
+-   [WriteParams](#writeparams)
+-   [RemoveParams](#removeparams)
+-   [Options](#options)
+    -   [Properties](#properties)
 
 ### S3BlobStore
 
@@ -85,6 +87,7 @@ Create read stream
 ##### Parameters
 
 -   `opts` **([ReadStreamOptions](#readstreamoptions) \| [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String))** options or object key
+-   `s3opts` **[ReadParams](#readparams)?** additional S3 options
 
 Returns **ReadableStream** readable stream of data for the file in your bucket whose key matches
 
@@ -95,7 +98,7 @@ Create write stream
 ##### Parameters
 
 -   `opts` **([Options](#options)&lt;[WriteParams](#writeparams)> | [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String))** options or object key
--   `s3opts`  
+-   `s3opts` **[WriteParams](#writeparams)?** additional S3 options
 -   `done` **function ([Error](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error), {key: [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)})** callback
 
 Returns **WritableStream** writable stream that you can pipe data to
@@ -106,7 +109,8 @@ Remove object from store
 
 ##### Parameters
 
--   `opts` **({key: [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)} | [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String))** options containing object key or just key
+-   `opts` **([Options](#options)&lt;[RemoveParams](#removeparams)> | [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String))** options or object key
+-   `s3opts` **[RemoveParams](#removeparams)?** additional S3 options
 -   `done` **function ([Error](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error))** callback
 
 #### exists
@@ -115,27 +119,19 @@ Check if object exits
 
 ##### Parameters
 
--   `opts` **({key: [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)} | [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String))** options containing object key or just key
+-   `opts` **([Options](#options)&lt;[ExistsParams](#existsparams)> | [String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String))** options or object key
+-   `s3opts` **[ExistsParams](#existsparams)?** additional S3 options
 -   `done` **function ([Error](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error), [Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean))** callback
 
 ### 
 
-### WriteParams
-
--   **See: <https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property>**
-
-S3 `putObject` params
-
-### Options
+### 
 
-Type: [Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)
+### ExistsParams
 
-#### Properties
+-   **See: <https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#headObject-property>**
 
--   `key` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** object key
--   `name` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** `key` alias
--   `filename` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** `key` alias
--   `params` **S3Params?** additional S3 options
+S3 `headObject` params
 
 ### ReadStreamOptions
 
@@ -155,4 +151,25 @@ S3 client
 
 S3 `getObject` params
 
-### 
+### WriteParams
+
+-   **See: <https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property>**
+
+S3 `putObject` params
+
+### RemoveParams
+
+-   **See: <https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#deleteObject-property>**
+
+S3 `deleteObject` params
+
+### Options
+
+Type: [Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)
+
+#### Properties
+
+-   `key` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** object key
+-   `name` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** `key` alias
+-   `filename` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** `key` alias
+-   `params` **S3Params?** additional S3 options