Then, you can modify the file (.../classes/search.php) to substring all the searches with (%) variable or whatever you want.
From line 190 to 197
AND sw.word LIKE
'.($word[0] == '-'
? ' \''.pSQL(Tools::substr($word, 1, PS_SEARCH_MAX_WORD_LENGTH)).'%\''
: '\''.pSQL(Tools::substr($word, 0, PS_SEARCH_MAX_WORD_LENGTH)).'%\''
);
if ($word[0] != '-')
$score_array[] = 'sw.word LIKE \''.pSQL(Tools::substr($word, 0, PS_SEARCH_MAX_WORD_LENGTH)).'%\'';
Like this
AND sw.word LIKE
'.($word[0] == '-'
? ' \'%'.pSQL(Tools::substr($word, 1, PS_SEARCH_MAX_WORD_LENGTH)).'%\''
: '\'%'.pSQL(Tools::substr($word, 0, PS_SEARCH_MAX_WORD_LENGTH)).'%\''
);
if ($word[0] != '-')
$score_array[] = 'sw.word LIKE \'%'.pSQL(Tools::substr($word, 0, PS_SEARCH_MAX_WORD_LENGTH)).'%\'';
But with this the search makes much more effort and the performance probably will be affected or can cause an overload.
it would be better to use something like a wildcard, but I don't know of any on presta.