Aww, poor Felix! Sounds like he would benefit from some extra Omega3 for sure. Like rainbow said, the amount found in pet food is pretty negligible. You might want to pick up some capsules from a health food store (I like the ones that use sardines, anchovies or krill instead of salmon, for environmental reasons). You can use a pin to poke a hole in one end and squeeze a couple drops in Felix's wet food, gradually increasing the amount to half a capsule or so per day (there really are no set guidelines on how much to use so find out what Felix can tolerate and go from there).
Couple other things come to mind. How is Felix's weight? Any possibility that you can eliminate the dry food from his diet? The high amount of starch in kibble (and the potato starch in Orijen in particular) is thought to be pro-inflammatory and would undo the benefits of adding Omega3. If you could feed just the Wellness canned, that would be ideal.
Some other supplements worth considering are MSM and green lipped mussel extract. Is Felix on any pain meds right now?
"To close your eyes will not ease another's pain." ~ Chinese Proverb
“We must not refuse to see with our eyes what they must endure with their bodies.” ~ Gretchen Wyler