Your client seems to randomly mispronounce some words. This does not seem to be because of a speech impediment. It is not because they are sloppy because most of their speech is fine and at a normal speed.
They may have particular trouble with unusual names or brand names. It may seem as if they are not paying attention. For example, they may see a label on their device every day and still mispronounce the word. If this is your name, it may even seem disrespectful. But it is a common problem for many people with dyslexia.
Dealing with unknown or unusual words is one of many possible symptoms of dyslexia. Because dyslexic people have trouble discriminating individual sounds, they cannot help themselves by splitting words into easy smaller chunks.
This means that they will often mispronounce words. What's more, they will find it very difficult to correct their mispronunciation or even become aware of it. For instance, they will say things like 'avalayble' instead of 'available' or 'audiable' instead of 'audible'. They will particularly struggle with foreign names (like Worczak) or unusual brand names (like Samsung).
In daily interactions, this behaviour does not require correction. You should be aware of it and not get impatient with the dyslexic person when they mispronounce common things. It only rarely results in misunderstanding, and when it does it is easy to correct it.
In teaching or in other context where accuracy is very important (such as legal proceedings), you can help a dyslexic person by helping them break down the difficult words into chunks. They can also use mnemonic devices such as rhymes to help.