I have been trying to add these custom fiels into user account system of meteor under the profile, but it wasn’t success. I have a modal form, which is pop up to do that and below is my code on the events.
Template.profile.events({
'submit #saveBasicProfile': function(event, template) {
console.log("CLICK");
event.preventDefault();
var fullnameVar = event.target.fullname.value;
var titleVar = event.target.title.value;
var about_youVar = event.target.about_you.value;
Meteor.users.update( {_id:Meteor.user()._id}, 
        { $set: 
            [{ "profile.fullname"  : fullnameVar }, 
             { "profile.title"     : titleVar },
             { "profile.about_you" : about_youVar } ]
        });
//Router.go('/profile');
}   
});