Right now i have intel core i5-4690K @3.50GHz and im thinking to get the i7-8700K ofc i have to change my motherboard aswell but i want to know if i need to change my GPU i currently have GTX960-4GB.
No, it is better and cheaper to buy a 2 x 8gb kit to get a total of 16gb.
If you are multitasking and gaming, you need enough ram to comfortably hold all the active tasks.
Do not buy one 16gb stick,
You want to run in faster dual channel mode, and that requires a two stick kit.
And... buy ram only in a single kit. Buying two 8gb sticks may seem cheaper but ram must be matched and will be supported only in a single kit.
This is what my cart looks like right now https://imgur.com/a/aw8P44v or should i go with this mother board ? https://www.ultramalta.com/AORUS-Z370-Gaming-K3--Intel-Z370--Sck1151--DDR4-ATX-_p_1852.html
Your cart looks fine.
You need a cooler of some sort, and the other air options are puny and not suitable for an 8700K.
As to motherboards, the less expensive Z370 based motherboard looks ok to me.
If you like RGB "bling" the aorus is OK too.
This is what my cart looks like right now https://imgur.com/a/aw8P44v or should i go with this mother board ? https://www.ultramalta.com/AORUS-Z370-Gaming-K3--Intel-Z370--Sck1151--DDR4-ATX-_p_1852.html
The first one looks fine.... What GPU are you planning to get?