unfortunately we do not support content-only deployment. However, there are several ways in which you can accommodate your client:
1. You can point your local installation to work with the remote database (the same one your client is working with)
2. If you are working only on controls and modules (not working with pages and content) you can safely upload your files and the clients work in database will remain intact.
Of course, you should always backup the database and your client's work before any deployment. I hope you'll find this information helpful. Let us know if there is anything else we can do for you.
All the best,
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.