Search not working correctly

I'm in the customer view, Tab E-Mail, listing Mailboxes.

Listing: E-Mail Address | Realname | ... martin@maurer.com | Martin Maurer

Searching for Realname: "m" -> works "Martin" -> works "Martin Maurer" -> doesn't work "Maur" -> works "Maurer" -> doesn't work

Also it seems that in some search fields i'm able to use % signs. Hopefully this is not passed directly to the database...