Identify by clientID

Hi there, I just found this tool and it looks amazing.

Though with my current setup I’m unable to make unique visitors.
I have some sort of unique setup where all requests come from one server.
This will then get the page for the client and sent the page to the client. In some ways it will look like a proxy, though it isn’t

So request in the access log will have lines like these: - - [26/Jan/2014:03:38:56 +0100] “POST /api/ HTTP/1.1” 200 2416 "" - - [26/Jan/2014:03:38:56 +0100] "GET /?client=bz10z-LW69PCQXMJA8Z17CDB17_K2JYH7M4X8G6B90E6B3F

How could I change piwik so the clientid will be used as unique identifier, since now I only have one unique visitor which in the above example is

With regards,