How Should I Build Bard Like A Tank Or Like A Support Caster?

Experiment. Seriously, just try things, even if they seem crazy. You might find something unique that works for you. Being unorthodox can be a powerful tool :)

bard usually helps out with cc rather than dmg, so i would build cdr, mana, ap for his heal and movement speed so he can stack passive

Well whatever you do hit the CDR cap. Mobis are a must on him. And a Sighstone (duh).

Something to consider with starting items is that the Meep and the auto that procs it are separate sources of damage, proccing twice.

Personally I build him utility heavy, with a bit of tankiness to soak up a few skillshots. Bard is similar to Lulu, you might get focused simply because its so easy to delete you, then your not very effective. Unlike Lulu you require a bit more finesse, so surviving to position for stun is important