Create a composer.json in project root directory and copy paste the following composer configuration. Then run composer install.

{
    "name": "blog/your-name",
    "description": "my Official blog",
    "repositories": [
    {
      "type": "composer",
      "url": "http://wpackagist.org"
    }
    ],
    "require": {
        "php": ">=5.4",
        "johnpbloch/wordpress": "4.2"
    },
    "extra": {
        "wordpress-install-dir": "wp"
    }
}

Once done, copy wp/index.php to project root directory and update require( dirname( __FILE__ ) . '/wp-blog-header.php' ); to require( dirname( __FILE__ ) . '/wp/wp-blog-header.php' );.

Now run the WP at http://localhost/wp-project-root and continue with installation and you’re done.

References:

1. Using Composer With WordPress
2. Composer in WordPress
3. Giving WordPress It’s Own Directory