Generate an OR SQL statement in CakePHP 3 - cakephp

Question

I am converting some finds from cakephp2 to cakephp3.
I need to search on a first name and surname on a tutors table that are stored on different columns. According to the docs I needed to have a LEFT join bewtween the tables. I have used an or condition with 2 fields but it works like and 'and' condition if both parameters have a value.
My issue is
q1) I cant get the data with just the first name only , and the surname is null.
q2) I need to pass both first name and surname to get just those data with that name.
Not sure how to do this in cakephp3.
eg $a5='fred'; //just want all first names like fred
$a6=null; //sometimes this will be filled
$a3='2015-05-30';
$a4='2016-06-01';
$query3 = $this->Lessons->find()
->contain(['Tutors'])
->select(['lessons.id','lessons.lesson_date','tutors.id','tutors.first_name','tutors.last_name' ])
->where(['Lessons.lesson_date >' => $a3,'Lessons.lesson_date <' => $a4,
'OR' => [['tutors.first_name like' => '%'.$a5.'%'], ['tutors.last_name like' => '%'.$a6.'%']],
]);
foreach ( $query3 as $row) {
debug($row->toArray());
}
I didnt understand the docs on this point.
http://book.cakephp.org/3.0/en/orm/query-builder.html#advanced-conditions
UPDATE- tried this and this also just gives all the data with either 'at' or 'to' but it should be any names with both 'at' and 'to' in them.
$query3 = $this->Lessons->find()
->contain(['Tutors','Subjects', 'TutoringTypes','Terms','Students'])
->select(['lessons.id','lessons.lesson_date','tutors.id','tutors.first_name','tutors.last_name',
'subjects.id','subjects.name','terms.id','terms.title'])
->where(['Lessons.lesson_date >' => $a3,'Lessons.lesson_date <' => $a4])
->orWhere(function ($exp) {
return $exp->and_([
'tutors.first_name like' => '%an%',
'tutors.last_name like' => '%to%',
]);
});

Answer 1

Pay attention to the generated SQL. You either see it in DebugKit or debug it by calling $query->sql(). You're building a wrong query:
You generate OR ((... AND ...)) because you're using an and_. You probably want ... OR ....
->orWhere(function ($exp) {
return $exp->and_([
'tutors.first_name like' => '%an%',
'tutors.last_name like' => '%to%',
]);
});
You probably want OR. But passing the array directly to orWhere() would work as well.