Client connected AP

Is there anyway of tracing how a client is getting to the mikrotik? if I have a non Mikrotik access point with a static IP?

What does the logs say?

Time Jun/05/2013 13:05:15
Buffer memory
Topics
dhcp
info
Message default assigned 10.4.1.105 to XX:XX:XX:XX:XX:XX

no mention of ap

Where in your network is the Mikrotik device, is it upstream from the AP?
Have you tried Torch in /tools ?