How similar does a potential supervisors research have to be to mine? The proposal I’m shopping around revolves around three broad topics and I’m coming across a lot of academics who are experts in one or two of these areas and I have only been able to find one who hits all three, but working with him is not going to happen for various reasons. I have not been able to find a university that has, even multiple academics who can collaboratively meet all my specialties.

My question is, is it advisable to do your PhD under academics, who together aren’t experts in all the main topics you’re researching.

Also, if you’ve gone through a potential supervisor’s research and they have only ever used the quantitative method and your proposed study will be using the qualitative method, can they still adequately supervise you?
In a PhD, you are supposed to show that you can do independent research. Thus, in a perfect case, the supervisor would only advise you academically (e.g. "how to write good papers" or "how to find the right conferences to attend") and not with regard to contents.

If you want a supervisor that already knows the answers to all your problems and only lets you do the thesis for fun(ding), you might want to rethink your plan.

This is, of course, only about your research project itself. A PhD oftentimes contains other parts, like for example working for the advisor, either in their research group or as a TA, or not only working on your PhD project but also on other, publishable, projects together with your advisor. These need consideration from both sides. Can you find a supervisor where you can do valuable (both in knowledge and money) work and can the supervisor find a student who is capable of doing the tasks? But it is possible to work on one thing and write your PhD on another one. While it is helpful if both are related in some way, it is not always necessary; for example you could be a TA for first year classes to get your expenses covered while working on something that is not first year material. 

Overall, I think as long as your supervisor has a vague idea of your topic and comes from a related field, it should be possible to work something out. Of course it is always easier if your supervisor hand feeds you all solutions as they are the number one expert on your field, but if you have the skills and motivation, you should also be able to manage without. It might even be positive, as you will have to reach out to different academics and build connections, instead of only sitting together with your advisor for multiple years.

What might help you is just discuss with your potential supervisors. They should have the experience to properly assess the situation and whether or not you will be able to work together.