The hack requires changing this file: /plugins/search/flexisearch.php

The code changes are as follows:

Add the following at the top of the plgSearchFlexisearch function

$originalText = $text;

Look for the following code at the bottom of that function:

foreach($list as $key => $row) {
  if($row->sectionid==FLEXI_SECTION)
    $list[$key]->href = JRoute::_(FlexicontentHelperRoute::getItemRoute($row->slug, $row->categoryslug));
  else
    $list[$key]->href = JRoute::_(ContentHelperRoute::getArticleRoute($row->slug, $row->catslug, $row->sectionid));
}

and replace it with this:

foreach($list as $key => $row) {
  if($row->sectionid==FLEXI_SECTION)
    $list[$key]->href = JRoute::_(FlexicontentHelperRoute::getItemRoute($row->slug, $row->categoryslug));
  else
    $list[$key]->href = JRoute::_(ContentHelperRoute::getArticleRoute($row->slug, $row->catslug, $row->sectionid));
  if(stripos ( $row->title , $originalText ) !== false){
    $firstObject = $list[0];
    $list[0] = $list[$key];
    $list[$key] = $firstObject;
  }
}