What is he trying to do?

um yeah stay away from him, not because of the age difference (though that is weird, he should not go after a 16 year old, i don't know where you live but it is kind of a child protection law here in USA ) but because he is not looking for a friendship or anything he is looking for a child partner, which is a form of ual abuse. He is doing those things to make you trust him and make you believe that he cares about you so you will be comfortable around him. The horses was to show off (see what i have) like if a little kid wants friends to like him he will make his parents get him all the popular toys to draw the other kids in) basically every little girl likes horses. So I'd stay away, it seems this guy only wants from you