views.py

def client_create(request):
    if request.method == "POST":
        user_form = UserForm(request.POST)
        client_form = ClientForm(request.POST)
        
        if user_form.is_valid() and client_form.is_valid():
            user = user_form.save()
            client = client_form.save(commit=False)
            client.user = user
            client.save()
            
            return redirect(client)
    ...