Login with custom login form in wordpress OR sign in with custom form

global $user_ID, $username, $password, $remember;

//We shall SQL escape all inputs
$username = esc_sql(isset($_REQUEST['username']) ? $_REQUEST['username'] : '');
$password = esc_sql(isset($_REQUEST['password']) ? $_REQUEST['password'] : '');
$remember = esc_sql(isset($_REQUEST['rememberme']) ? $_REQUEST['rememberme'] : '');

if($remember) $remember = "true";
else $remember = "false";
$login_data = array();
$login_data['user_login'] = $username;
$login_data['user_password'] = $password;
$login_data['remember'] = $remember;


$user_verify = wp_signon( $login_data, false );

REF : https://codex.wordpress.org/Function_Reference/wp_signon