Meta query date column add [x] days to validate

On top of my head this should be something like:

'meta_query' => [
        'key'     => '_EventEndDate',
        'value'   => [ $start, $end ],
        'compare' => 'BETWEEN',
        'type'    => 'DATETIME'
    ]

You would need to calculate boundaries yourself before passing to the query in this case.

See Custom Field Parameters in Codex for full documentation on parameters available for meta queries.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)