Woocommerce - extend product search form - woocommerce

Question

I need to extend the functionality of product search form to be able to search for products by SKU. This searches only in the title and content. Have no idea.
<?php
if ( isset( $_REQUEST['product_cat'] ) && ! empty( $_REQUEST['product_cat'] ) ) {
$optsetlect = $_REQUEST['product_cat'];
} else {
$optsetlect = 0;
}
$args = array(
'show_option_all' => __( 'All categories', 'domain' ),
'hierarchical' => 1,
'hide_empty' => 0,
'class' => 'cat',
'echo' => 0,
'value_field' => 'slug',
'selected' => $optsetlect
);
$args['taxonomy'] = 'product_cat';
$args['name'] = 'product_cat';
$args['class'] = 'selectpicker dropdown-select';
?>
<form role="search" method="get" action="<?php echo esc_url( home_url() ); ?>">
<input type="hidden" name="post_type" value="product">
<div class="input-group">
<input id="woocommerce-product-search-field-<?php echo isset( $index ) ? absint( $index ) : 0; ?>" name="s" placeholder="Search products" type="text" autocomplete="off">
<div class="input-group-append">
<?php echo wp_dropdown_categories( $args ); ?>
<button class="btn btn-primary" type="submit">
<span class="ec ec-search"></span>
</button>
</div>
</div>
</form>

Answer 1

You should try something like that:
add_filter( 'get_product_search_form' , 'woo_custom_product_searchform' );
function woo_custom_product_searchform( $form ) {
$form = '<form role="search" method="get" id="searchform" action="' . esc_url( home_url( '/' ) ) . '">
<div>
<label class="screen-reader-text" for="s">' . __( 'Search for:', 'woocommerce' ) . '</label>
<input type="text" value="' . get_search_query() . '" name="s" id="s" placeholder="' . __( 'My Search form', 'woocommerce' ) . '" />
<input type="submit" id="searchsubmit" value="'. esc_attr__( 'Search', 'woocommerce' ) .'" />
<input type="hidden" name="post_type" value="product" />
</div>
</form>';
return $form;
}