May i ask what current AMD processor and power supply you are currently using? The i5 4690k is a solid gaming processor and will require a Z97 motherboard to overclock. Honestly, the GTX 660 isn't a very powerful processor and an i3 4160 would be enough for it. My personnel recommendation is (if your PX is primarily for gaming) is this:
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Pentium G4560 3.5GHz Dual-Core Processor ($59.99 @ SuperBiiz)
Motherboard: ASRock H110M-HDS Micro ATX LGA1151 Motherboard ($44.99 @ SuperBiiz)
Memory: Corsair Vengeance LPX 8GB (1 x 8GB) DDR4-2666 Memory ($52.99 @ Amazon)
Total: $157.97
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-03-25 15:28 EDT-0400
The G4560 is a solid entry level gaming processor which can be paired with cards like the RX 470/480/1060. This would be a very nice cheap option and you can also sell your current DDR3 ram for some cash. If you want to spend more cash, i would not recommend getting a better processor but rather a better graphics cards like the three i mentioned above. If you are not upgrading for gaming, i would still recommend the same prcessor/mobo/ram that i mentioned above but instead of upgrading your graphics card, i would recommend you get a reliable and fast SSD:
PCPartPicker part list /
Price breakdown by merchant
Storage: Samsung 850 EVO-Series 250GB 2.5" Solid State Drive ($93.99 @ Amazon)
Total: $93.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-03-25 15:32 EDT-0400
I would also recommend this exact card (RX 480) as its currently at a very good prices and is coming free with a DOOM game code.
https://www.newegg.com/Product/Product.aspx?Item=N82E16814131706&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker,%20LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=