Recently started watching some of Wickd games and he said on stream that he uses full ad, does that mean only red/quints or yellow/blue also ad? :S

Also isn't arpen much better? most other riven guides suggest arpen

with exhaust,ignite and full ad runes you cen pretty easy land firstblood solotop. sure, arpen runes are way better lategame, but with the huge advantage earlygame you can freefarm, because the enemy is scared and get money through farm/ganks easier. if you fail that, your endgame wil llack a bit. higher rist = higher reward ... i guess

Honestly, I would just stick to using ArPen since you'll be purchasing a **** ton of AD later in the game. Although that ArPen also helps your early game damage as well, especially if you're dealing true damage on targets. But if you're going for a pubstomp then going AD Marks and Quints isn't so bad. AD also helps your shield...so paired with Defensive masteries and runes you'll prolly be scary.

AD Marks and Quints vs ArPen Marks and Quints. (Both with Doran's Blade)
25.3 AD + 6 ArPen vs 13 AD + 31 ArPen
edit: above also includes Masteries...

Also, the Glyphs and Seals give pretty low amounts of AD. It'd be better to go Magic Resist or CDR for Glyphs and Flat Armor Seals.

Full AD... I hope that means just marks/quints.

And compared to ArPen, it just comes down to preference.
Use what you have.
If you don't have either... or you have both....
I think the Arpen is quite strong, but AD helps Riven A TON. All her abilities scale with AD, even her passive and shield. So the Early AD boost means a lot for her I think.