CRM-18568 Api gives error when using 'LIKE' with pseudoconstant fields

To replicate

Create custom field (used for contact) of html type (basically those which register field option on Option value table)- checkbox/select/radio - any data type. Say Select field with options
custom_15 => ('option 1'=> 'a', 'option 2' => 'b');
2. On using advance filter array(LIKE => '%a%') it throw fatal error
"error_message": "'%a%' is not a valid option for field custom_15"

Comment by Monish:
So we need to extend _civicrm_api3_api_match_pseudoconstant() to support special character '%' on using 'LIKE' operator

Response by Eileen
@monishdeb - the minimum form of support would be to trim from the start & finish. But, are we trying to support

array('custom_10' => array('LIKE' => '%dakota%'));

for when people really do want to find north & south dakota or

array('LIKE' => '%big%house%'));

to find 'big house', 'my big house', 'my bigger house'

etc.

If we want to support the variants I'm not sure if that adds a security consideration.