The RadFilter does not support build-in the desired functionality. It formats the expressions in sql like format. However to achieve the desired functionality you could try using the AppyExpressions event where you could iterate over the RadFilter expressions or build yours. Also into this event you could create and add the expression though the existing QueryProviders. On the following link you could find a simple example of that:
(Handling the AppyExpressions event handler section)
I hope this helps.
All the best,
the Telerik team