Change the ext_tables.php file in the typo3conf/ext/yourext , find your table and add the searchFields property to your ctrl section as a list of fields separated by commas to search in:
$TCA['tx_yourext_table'] = array( 'ctrl' => array( 'title' => 'Title of your table', 'label' => 'title', 'tstamp' => 'tstamp', 'crdate' => 'crdate',
Remember to clear all caches after that, works in 4.6.3
There is official information when and why it was changed
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