Using meta_query With WP API V2

functions.php

<?php

function my_allow_meta_query( $valid_vars ) {

	$valid_vars = array_merge( $valid_vars, array( 'meta_key', 'meta_value', 'meta_query' ) ); // Omit meta_key, meta_value if you don't need them
	return $valid_vars;
}
add_filter( 'rest_query_vars', 'my_allow_meta_query' );

simple-query.php

<?php
$args = array(
	'meta_query' => array(
		array(
			'key'     => 'fruit',
			'value'   => 'banana',
		),
		array(
			'key'     => 'animal',
			'value'   => 'lion',
		),
	),
);
$query = new WP_Query( $args );