In Cloudfront with mutliple origins (s3 buckets), How can we redirect request to a particular bucket based on the pattern?

We’ve different S3 buckets for different clients. We are storing the corresponding client related files directly in the buckets. There is no directory inside any bucket.

We’ve also created a Cloudfront distribution with multiple origins (s3 buckets) and cache behaviors. Everything works fine. However, I’ve a little confusion regarding path pattern in cache behaviors.

How do I create a pattern that will redirect the request to a particular origin (bucket)? The problem is that if I define the path pattern for example, bucketname/* , it searches under http://ift.tt/1NCW13X. However we want it to get the file from bucketname.s3.aws.com/ as we don't have directory inside the bucket. How can we achieve this ?

Any help will be highly appreciated!