|You'll need a second router that's wireless capable to accomplish this.|
For information on how to set this up, click on my name above in this response and read my “how-to” guide titled, “Add a second Router to your LAN”
You'll want to use the scenario where you have separate subnets and interconnect the two routers using the "LAN port to WAN port" scenario.
It's worth noting, you'll want to have the wireless router connected directly to the internet and the private LAN router connected to it. Setup this way it prevents the wireless LAN from accessing the private wired LAN.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.