If you're out & about McDonald's/Burger King have clean, fully equipped bathrooms that you don't need a key to enter. Just Google them on Google maps. There's usually always one around the corner.
If you use a public bathroom in a park or somewhere similar, there is usually a toilet paper dispenser at the entrance but always carry tissues with you just in case. Also, there's usually at least 1 western toilet. Just look through the several stalls to find it. Unless you have already perfected the art of squatting ;-)