Is there any way to fire heartbeat API from for website visitors?

As Mark Kaplun says in the comments, you shouldn't do it. But here's how to enqueue the heartbeat script for all users on the public side... if you really, really want to overload your server.

add_action( 'wp_enqueue_scripts', 'enqueue_heartbeat' );
function enqueue_heartbeat() {
  wp_enqueue_script( 'heartbeat', includes_url( js/heartbeat.js ) );
}