First of all I don't think he should have AD scalings, nothing about him says AD to me. AP tank would make him WAY more appealing.
I think that's the biggest buff you could give him. Make him scale on AP instead of AD and slightly buff his base damages.
So scaling would be
Passive: 4-10% Max health depending on level < A slight nerf to not make him obsurd with scaling changes, since he would be doing more damage on his abilities.
Q: 40/55/70/110/140 + 45% AP
E: 30/45/75/100/125 + 15% TOTAL armor + 15% TOTAL MR + 10% AP
E: Shockwave: 50/120/160/200/230 + 25% Total armor + 25% Total MR + 10% AP
R: 150/250/350 + 35% AP