I’d use the built-in create_superuser and log the user in before making any requests. The following should work:
from django.contrib.auth.models import User
from django.test.client import Client
# store the password to login later
password = 'mypassword'
my_admin = User.objects.create_superuser('myuser', 'myemail@test.com', password)
c = Client()
# You'll need to log him in before you can send requests through the client
c.login(username=my_admin.username, password=password)
# tests go here