Currently you can only search by the LAN mac address in cnMaestro (2.2.1). Since some organizations authenticate using the wireless mac address, then this mac address should also be searchable (and used in various other contexts like the API).
Sorry, should have given an example. Epmp clients have multiple Mac addresses, and currently it seems the LAN MAC is the only one that is searchable. The wireless MAC is more important to some companies.