Here is a quick snippet of code that can be executed to locate and display the Client Cache folder:

SHOW ON DISK(GET 4D FOLDER(Database Folder))

To get the Client Cache folder this should be run in the 4D Remote instance.

On Windows Vista/7 the Client Cache folder is located at:
{Disk}:\Users\{user}\AppData\Local\4D\DatabaseName_Address

On Windows XP/2003 the Client Cache folder is located at:
{Disk}:\Documents and Settings\{user}\Local Settings\Application Data\4D\DatabaseName_Address

On Mac OS X the Client Cache folder is located at:
{Disk}:Users:{user}:Library:Caches:4D:DatabaseName_Address:

Where {Disk} is the volume name and {user} is the user name.