Why don't you post pictures? That way we will see exactly what you have. If the plant is flowering, you should know it's a Clematis. All Clematis have opposite leaf arrangement. Look for where the leaves come out of the stems.
Poison ivy has alternate leaf arrangement.

I will try to post pics. Thank you for the leaf arrangement tip. It is flowering, I know PART of it is clematis, it just went so vine-ish this year.

Poison ivy has "leaves of three"

Clematis are supposed to be "vine-ish" They don't always take off on their third year. Many of mine waited longer....It is normal for them to grow bigger and longer every year as they get older until they reach mature size.