No, they have the same meaning.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
zapeti1235I was looking all over for you.This one is disconnected from the present. The activity is entirely in the past. There is no limit to how far in the past it occurred.
zapeti1235I've been looking all over for you.This one is connected to the present. The activity continues up to the moment you say the sentence,
zapeti1235So, when I do find this person, do I say I was looking all over for you?You can. I would say, "I've been looking all over for you" because it seems from your description that the looking continued up to the present moment.