OK, the basic principal of what I said still holds true - the only way you can pass the cname to the controller page is to pass it as a GET variable in the URL, something like this:
<a href="controller?EVENT_NAME=EDITCLIENT_LINK&cname= <%=cname%>"><%=cname%></a>
Then, the same way as you access the EVENT_NAME variable on controller, you can also access cname. By the way, what language are you using here? Not one I'm familiar with, but I've hopefully got the code write by extending what you posted.