Haluan, että sinä rakastat minua = I want that you love me.
Haluan sinun rakastavan minua = I want you to love me.
What should be partitive? The verb "haluta"? Verbs are only inflected according to person, tense, and number. The only thing in partitive case here is the pronoun "minua". In this instance it's irrelevant whether the action is incomplete because it's impossible to be complete, and the reason for that is that fact that the verb acting on it, which is "rakastaa", is an irresultative verb. The object of an irresultative verb should be in partitive case.