How to change the search action in wordpress search bar?

Question

Create a new post and publish it.

The title is my test for search, content in it is as below:

no host route

Check what happen in wordpress database.

 select post_title from wp_posts
     where post_content like "%no%"
       and post_content like "%route%"
       and post_content like "%to%"
       and post_content like "%host%";

The post named my test for search will not be in the select's result.
Type no route to host in wordpress search bar,and click enter. The post named my test for search shown as result.

I found the reason that the webpage contain to ,in the left upper side corner ,there is a word Customize which contains the searched word to.
How to change such search action in wordpress serach bar?
I want to make the search behavior in wordpress saerch bar, for example ,when you type no route to host, equal to the following sql command.

select post_title from wp_posts where post_content like "%no%route%to%host%";

All the plugins in my wordpress.

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Answer 1

There's this addition to the SQL WHERE clause on wp-includes/class-wp-query.php:1306:

<?php
// wp-includes/class-wp-query.php:~1306

foreach ( $q['search_terms'] as $term ) {
    //...
    $like = $n . $wpdb->esc_like( $term ) . $n;
    $search .= $wpdb->prepare( "{$searchand}(({$wpdb->posts}.post_title $like_op %s) $andor_op ({$wpdb->posts}.post_excerpt $like_op %s) $andor_op ({$wpdb->posts}.post_content $like_op %s))", $like, $like, $like );
    // ...

Therefore, I'd hook into the pre_get_posts, and supply the words of the query as explicit "search_terms", since they get added into that clause, with the LIKE modifier just as you said were looking for!

So, we might do something like this:

<?php
// functions.php

function fuzzify_query(\WP_Query $q) {
    if (true === $q->is_search()
        && true === property_exists($q, 'query')
        && true === key_exists('s', $q->query)
    ) {
        $original_query = $q->query['s'];
        $words          = explode(' ', $original_query);
        $fuzzy_words    = array_map(
            function($word) {
                return '%'.$word.'%';
            },
            $words
        );

        $q->query_vars['search_terms'] = $fuzzy_words;

        return $q;
    }

    return $q;
}

 add_action('pre_get_posts', 'fuzzify_query', 100); // Or whatever priority your fuzziness requires!