Pretty much with your build, try stacking cold damage, frozen orb damage, electrocute damage.
Pretty much this, check the front page for the legendaries with cold damage. Then add in pieces with frozen orb damage. If you have room on other pieces for Electrocute (you shouldn't really be using it THAT much anyways to matter but if your not sacrificing anything important go ahead). That's the basics, may want to also take a look on the official site at all the legendaries for special effects you may like and look towards farming them as a lot of it can be preference for your overall build.
Also with that, depending on your current Wizard build "BiS" legendaries can change drastically. Would need much more info than your giving us.