My "real wireless client" mean the computer connected to the network using wireless, not through other method.
This is because I had done some testings. I tested with 2 computers. First computer connected to my wireless router by using wireless network adapter, while the second computer connected to my wireless router using wired connection. I had noticed that the MAC Address of the wired network adapter in second computer (the one using wired) are recorded as well, either as source address or destination address.
This make me very hard to program my application to detect which MAC address is the MAC address of the wireless network adapter, not the wired network adapter.