The AirPort Extreme must connect to the Fios modem/router using a wired Ethernet cable connection, since it cannot connect wirelessly. However, the AirPort Extreme would be able to connect using wireless only to another AirPort Extreme. See an option below for more details.
Ethernet cabling....(always the best choice for top performance)..... can be run up to 328 feet or (100 meters) with no signal loss. Use either CAT5e or CAT6 wiring.
I'm not recommending them, but if you don't want to run the Ethernet cable, some users have had decent results by using a pair of Ethernet over powerline adapters to run an "Ethernet" signal over the existing AC powerlines in their homes.
The theory with these devices is that you already have the wiring in place, you just need the adapters.
In practice, things do not always work as well as the theory might suggest. So, if you decide to try a pair of the adapters.....(any computer/electronic superstore will have a selection from which to choose).....make sure that you understand the store's return policy before you buy.
Another possible option might be to keep your current AirPort Extreme exactly where it is and add another AirPort Extreme approximately half way between the "main" AirPort Extreme and the general area where you need more wireless coverage.
In this type of setup, the additional AirPort Extreme can connect back to the main AirPort Extreme using only a wireless connection. The connection speed will not be as good as using Ethernet cabling to connect devices together, but the wireless solution can often work OK.
Again, it would be wise to understand the store's return policy, since you won't know how well things will work until you try them out in your home.
