functions.php

<?php

/**
 * Add Search to Menu
 *
 */
function be_add_search_to_menu( $menu, $args ) {
	if( 'header' == $args->theme_location )
		$menu .= '<li class="menu-item search"><a href="#"><i class="icon-search"></i></a>' . get_search_form( false ) . '</li>';
	return $menu;
}
add_filter( 'wp_nav_menu_items', 'be_add_search_to_menu', 10, 2 );

global.js

jQuery(function($){

	// Open Search	
	$('.genesis-nav-menu .menu-item.search a').click(function(e){
		$('.genesis-nav-menu .search-form').css('display', 'block');
		$('.genesis-nav-menu .search-form input[type="search"]').focus();
		e.preventDefault();
	});
	
	
	// Close Search
	$(document).mouseup(function (e){
		var container = $('.search-form');
		if (!container.is(e.target) // if the target of the click isn't the container...
        && container.has(e.target).length === 0) // ... nor a descendant of the container
    	{
        	container.hide();
    	}
	});
});

style.css

.genesis-nav-menu .search-form {
	background: #fff;
	border-top: 4px solid #76bd22;
	position: absolute;
	top: 0;
	right: 0;
	width: 100%;
	display: none;
}

.genesis-nav-menu .search-form input[type="search"] {
	color: #5d5d5d;
	font-size: 16px;
	line-height: 30px;
	outline: none;
	border: none;
}

.genesis-nav-menu .search-form input[type="submit"] {
	background: transparent url(images/search.jpg) no-repeat center center;
	background-size: 20px 19px;
	border: none;
	width: 42px;
	height: 50px;
	position: absolute;
	top: 0;
	right: 0;
	min-width: 0;	
}