Resolve a service manually in Web API using Autofac

How can I resolve a service manually in a Web API project using Autofac. I have a class called Foo. Foo is instantiated by Activator.CreateInstance by another class that I have no control over, which means it would call the paramaterless constructor.

I have a few properties that need to be injected in the Foo class. Now since the calling class calls the paramaterless constructor, I need to resolve these properties manually.

public class Foo
{

    private IService Instance;

    public Foo()
    {
        //How do I get the per request lifetime scoped dependency resolver here
        IService = (Dependency Resolver).Resolve<IService>();
    }

}