AlwaysON - Force users connection to use Readable Secondary Nodes
There is no way to complete this with just SQL Server and the interfaces it exposes. In order to do this you'll either need an appliance between the clients and SQL Server (the users connect to the appliance endpoint and the appliance does the redirection) or you can implement your own through a cname and some type of configurable load balancer like an F5.

There is nothing in 2016 to change this behavior AFAIK.