If you are not feeling any issues, but think an upgraded cpu might be good. And are considering uping the core count, and base speeds by going R5.
My advise would be wait.. totally skip the 1600/2600 series of cpus, and wait for the 3000 series as those will be better, as of yet it is all speculation, but everything iv read/heard is they have made some decent improvements.
So unless its an urgent upgrade, i would 100% say wait for Ryzen 2 (3000, not Gen 2), your mobo will only likely need a bios update. Don't look at Gen 1 unless you come across a real bargin, the price saving is'nt that big.
That being said, your current cpu is decently paried with the Gpu you have, so technically is'nt a bottle neck, you wouldn't see a massive spike in fps, yeh you may see a few more, but it wouldn't be drastic. More cores/threads just really allows the overall system to be less strained to be fair.
Overall you would be going from 4 real cores to 6 real cores but 12 with hyper threading, so it would be a big upgrade to the overall system rather then just gaming.