Make Failover for Two Mediums (Ethernet/WiFi) for Pfsense

Hi.

I have installed Pfsence in my network with different subnets. For a specific subnet I want to make a failover link at MikroTik Router v5.25 for two different mediums one in Fiber/LAN and other is Wireless to connect two centers connectivity with failover.

On both ends there will be MikroTik router and two Ethernet ports of each router will be used for LAN and Wireless points. On will be used for the Switch LAN. I just need the configration for both routers that if My Fiber/LAN point is disconnected then the traffic should be switched over the Wireless link.

Source side has Pfsence with a specif subnet from Pfsense and destination side will have switched network.

See the scenario in attached picture.
IMG_20150131_105935.jpg