I really want to adopt

My son is 4 months old, and I was speaking with my partner the other day saying that I would like to have two biological kids and then to adopt a third. He totally disagreed with doing that, he's happy to have more biological kids but doesn't want to adopt. I feel really upset now, i've wanted to adopt ever since I was young. I want him to think about but he just keeps saying nope I don't want that. How do I deal with this? I am so passionate about adopting a child.